Abstract: Methods 300 and systems 400 are provided for creating customizable user interface wrappers for a web application using a software development platform with a plug-in architecture 100. The development platform is used to create one or more declarative descriptions in a predefined plug-in format which define the customized user interface. The declarative description is accessed to generate the user interface wrapper, and the web application is enabled to operate using the user interface wrapper. The declarative description may be in the form of an XML file implemented as an extension listed in an extension directory of a plug-in. The attributes specified in the declarative description may be tailored to run the web application on a given platform, such as an operating system implemented on a predefined type of computer.